pin that provided a positive mechanical lock to prevent accidental disengagement of the connectors. This design required special connectors on both the male and female side in order to work, meaning that all connectors in an installation would need to be replaced to see a real benefit to the locking feature. The expense of this proposition as well as the unpopularity of the connector itself among technicians led the locking feature to eventually be dropped, and locking connectors are no longer manufactured. The locking connectors that are still found occasionally in installations or spare parts bins are often referred to as "Union Connectors", though the Union Connector brand now features only standard non-locking stage pin connectors. Since their introduction, stage pin connectors have been available in 20 A, 30 A, 60 A, and 100 A varieties, with the higher-current connectors being not only far larger in size but also with a different pin configuration for ground, neutral and line. Care must be taken when repairing or building these larger connectors, because ground is on the outside pin and neutral is in the middle, with the far pin still being the line. Cabling Extension cables Most extension cables made with 20 A stage pin connectors use 12/3 type SOOW or SJOOW cable which has three individually insulated 12 awg (American Wire Gauge) stranded conductors inside a larger jacket. The internal insulation is usually colored black (for line), white (for neutral) and green(for ground). This cable configuration can safely handle the full 20 ampere rating of the connector. The designation SOOW or SJOOW refers to the cable's insulation construction and type. SJ— (300 volts, maximum) and S— (600 volts, maximum) are both "most severe" service cordage. This type of cable is very hard-wearing, resistant to oil and moisture, and resists the kinking that can result in internal conductors unlaying and twisting, which is a common problem with the SJTW cable often used in household-grade extension cords. However, older cable made using natural rubber is susceptible to dry-rotting, particularly with the heat generated by lighting equipment. This can cause the insulation to fail and expose or short circuit the conductors leading to shock or fire hazard if old cable is not inspected regularly and replaced as needed. Multicircuit cable Some stage pin extension cables may be constructed from cable with six or more conductors. This cable can be fitted with multiple stage-pin connectors